| primary atelectasis | <chest medicine, paediatrics> A nonexpansion of the lungs after birth is known as primary atelectasis. Secondary atelectasis can occur at any age but is common in infants due to hyaline membrane disease. This form may also be seen in patients after surgery (general anaesthesia). See: atelectasis. (05 Mar 1998) |
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| primary atypical pneumonia | An acute systemic disease with involvement of the lungs, caused by Mycoplasma pneumoniae and marked by high fever, cough, relatively few physical signs, and scattered densities on X-rays; usually associated with development of cold agglutinins and antibodies to the bacteria. Synonym: atypical pneumonia, Eaton agent pneumonia, mycoplasmal pneumonia. (05 Mar 2000) |
| primary biliary cirrhosis | <gastroenterology> A rare form of liver disease which results in the irreversible destruction of the liver and bile ducts. The cause is unknown, but is thought to be an autoimmune mechanism. (06 Mar 1998) |
| primary brain tumour | <neurology, oncology> May be subdivided into primary brain tumours and the more common, secondary brain tumours. Primary brain tumours (for example astrocytoma, craniopharyngioma, glioma, ependymoma, neuroglioma, oligodendroglioma, glioblastoma multiforme, meningioma, medulloblastoma) arise from the uncontrolled proliferation of cells within the brain. Secondary brain tumours occur from the spread of cancer into the brain from a distant cancerous organ (metastasis). Common symptoms of a brain tumour include headache, nausea, vomiting, seizures, change in mentation, neurologic symptoms and loss of memory. (06 Mar 1998) |
| primary brain vesicle | Each of the three divisions of the early embryonic brain (prosencephalon, mesencephalon, and rhombencephalon). Synonym: encephalic vesicle, primary brain vesicle. (05 Mar 2000) |
| primary bronchus | The main bronchus arising at the tracheal bifurcation and extending into the developing lung of the embryo. (05 Mar 2000) |
| primary butyl alcohol | Propylcarbinol, CH3CH2CH2CH2OH, the butyl alcohol of fermentation; isobutyl alcohol, isopropylcarbinol, 2-methyl-1-propanol, (CH3)2CHCH2OH; narcotic in high concentrations, secondary butyl alcohol, ethylmethylcarbinol, 2-butanol, CH3CH2CH(CH3)OH; and (05 Mar 2000) |
| primary carcinoma | <tumour> Carcinoma at the site of origin, with local invasion in that organ. (05 Mar 2000) |
| primary cardiomyopathy | Cardiomyopathy of unknown or obscure cause. A disease that affects mainly the heart muscle, sparing other cardiac structures and usually resulting in fibrosis, hypertrophy, or both. Synonym: idiopathic cardiomyopathy. (05 Mar 2000) |
| primary caries | Initial lesions produced by direct extension from an external surface. (05 Mar 2000) |
| primary cell | <cell biology> A cell or cell line taken directly from a living organism, which is not immortalised. (06 Mar 1998) |
| primary cell culture | <cell culture> Of animal cells, the cells taken from a tissue source and their progeny grown in culture before subdivision and transfer to a sub culture. (18 Nov 1997) |
| primary cell wall | <plant biology> A plant cell wall that is still able to expand, permitting cell growth. Growth is normally prevented when a secondary wall has formed. Primary cell walls contain more pectin than secondary walls and no lignin is present until a secondary wall has formed on top of them. (06 Mar 1998) |
| primary cementum | Cementum that has no cementocytes; may cover the entire root of the tooth, but often is missing on the apical third of the root. (05 Mar 2000) |
| primary centre of ossification | This is the first site where bone begins to form in the shaft of a long bone or in the body of an irregular bone. Synonym: punctum ossificationis primarium, primary point of ossification. (05 Mar 2000) |